Just assembled my Ender 3, was homing the Z Axis and Leveling the bed, etc. During which I heard this high pitched noise that the extruder makes as it travels upwards along its Z-Axis. Was hoping someone could help me diagnose the issue. Including a video showing said noise.
There's a cyclic aspect to the metallic noise that would point to a fan blade rubbing somewhere. It's difficult to determine from the video if your extruder fan is running while the carriage is moving, but that would be one place to examine. Even though the power supply doesn't move with the carriage, consider to check the fan within that unit as well. Any other fans on the system should be examined.
If you don't find a fan problem, consider to disconnect the z-axis coupler and command a z-movement. The z-stepper isn't moving fast enough to generate the high pitch sound heard in the video and disconnecting the rod should eliminate misalignment concerns of that motor.